Interrelated propeller and engine control



June 5, 1951 A, CATFORD 2,555,784

INTERRELATED PROPELLER AND ENGINE CONTROL 6 Sheets-Sheel l June 5, 1951 A. l.. cATFoRD 2,555,784

INTENRELATED PROPELLER AND ENGINE CONTROL Filed sept. 11, 194e e sheets-sheet 2 Inventor any?! l Egan A [lor/ley June 5, 1951 -A. l.. cATFoRD 2,555,784

INTERRELATED PROPELLER AND ENGINE CONTROL `6 Sheets-Sheety 5 Filed Sept. 1l, 1946 Y Inventor A' L lay June 5, 1951 Y 1A. L. cATFoRD 2,555,784

INTERRELATED PROPELLER AND ENGINE CONTROL 6 Sheets- Sheet 4 Filed Sept. 1l, 1946 5 p Inventor Adi-gan L. Caford y M2M A Itullley June 5, 1951 A. L. cATFoRD INTERRELATED PROPELLER AND ENGINE CONTROL Filed Sept. l1, 1946 6 Sheets-Sheet 5 Adm L aww-4 MMP@ A llorney June 5, 1951 A. cATFoRD INTERRELATED PROPELLER AND ENGINE CONTROL Filed Sept. 11, 1946 M m a Adr/an L.

Patented June 5, 1951 INTEERELATED PROFELLER AND ENGINE CONTROL Adrian Leslie Catford, Hampton, England, as-

signor Vto D. Napier & Son Limited, London, England, a company of Great Britain Application September 11, 1946, Serial No. 696,101 In Great Britain September 17, 1945 2 Claims. 1

Vgear and the engine throttles, a servomotor, conveniently referred to as a primary servomotor, by which the other and opposite main wheel of the differential gear can be rotated, a second and subsidiary servomotor controlled by an operating lever and by which a cage carrying the pinions of the differential gear can be rotated about the gear axis, a valve controlling the now of pressure .liquid to the primary servomotor, a capsule sublject on the one hand to boost pressure and on the `other hand to the opposite action of a separate spring this capsule being operative to set the valve controlling the primary servomotor, a camshaft rotatable by the subsidiary servomotor when this motor rotates the cage of the differential gear, a datum boost cam on this camshaft which acting through a lever can vary the force exerted by the said spring on the capsule and thus affect the setting of the valve of the primary servomotor, and a second cam on this shaft which is operative on the airscrew governor and the ignition control. The valve of the primary servomotor is a piston valve which is convenientl 1y constructed and arranged so that it oats between two diaphragms which serve as oil seals the valve being balanced on the one hand by the -tendency to move it in one direction due to the boost pressure on the capsule together with a spring acting on one end of the valve, and on the other hand by that spring which, as mentioned, acts on the capsule in opposition to the boost pressure.

The accompanying drawings illustrate how the invention may be carried out in practice. In these drawings,

Figure l is a diagrammatic representation of the apparatus.

Figure 2 is a sectional elevation of the apparatus as it be constructed, the section being in the plane of the line Z- in Figure 3 looking in the direction of the arrows.

Figure 3 is a section on the line 3-3 in Figure 2 looking .in the direction of the arrows.

(Cl. Uil-135.74)

Figure 4 is an end view showing the apparatus as seen from the lefthand side as it appears in Figure 3.

Figure 5 is a section on the line 5-5 in Figure 4 looking in the direction of the arrows.

Figure 6 is a sectional plan on the line 6-6 in Figure 2,

Figure '7 is a sectional plan on the line l-1 in Figure 2 with certain rotatable parts omitted.

Figure 8 is a section on the line 8 3 in Figure 3.

Figure 9 is a view showing the end of the apparatus as seen from the righthand side of Figure 3.

In the rst place the whole apparatus may conveniently be described in general terms with reference to the diagrammatic view in Figure 1, and subsequently the parts will be described more in detail and with reference to the other illustrations in which the parts are shown as they may be made in practice.

The operating lever A, through mechanism indicated at B, controls the subsidiary servomotor C which imparts rotation to the shaft D. The mechanism B by which the servomotor is controlled is preferably `constructed and operative as otherwise known. The `diiierential gear E which is used is preferably of the bevel wheel and bevel pinion type and the cage with the pinions E2 which carries a toothed rack El is rotated about the axis of the gear by a pinion DI meshing with the `rack El and `mounted on the shaft D of the servomotor C. This motor also transmits rotation .to a cam shaft F through `a gear wheel. D2 on the shaft D which meshes with a wheel FI on the shaft F. On the shaft F is a datum boost cam F2 and a second cam F3 the function of which will be described hereunder. A two armed lever G, GI pivoted at G2 has at the end of the arm G a roller GE which bears on the cam F2.

A capsule H, subject to boost pressure from the outlet of the supercharger H4 of the engine H5 through a pipe H6, bears at its upper end against an adjustable abutment and at its other end is connected to one end of a rod H I whose other end can act on and movea piston valve J which controls a servomotor J I which rotates a shaft J2 which carries one of the bevel wheels E3 of the differential gear E. A coiled spring H2 abuts at one end on a disc or the like H3 Xed on the capsule rod H l while on the other end of this spring bears the end of the arm GI of the lever whose other arm G is acted on by the datum boost cam F2. The spring H3 acts in opposition to the action of the capsule on the valve J of the primary servomotor J l, the force exerted by the spring being varied through the cam F2 and the lever G, Gl. Means to be described hereunder are conveniently provided for effecting adjustments in the lever G, GI so as to vary the action of the cam F2 and determine the setting of the valve J.

The second cam F3 on the shaft F is operative on the airscrew governor M and ignition control mechanism MZ. A shaft K carries a lever Kl the end of which bears on the surface of the cam F3 with which it is maintained in contact by pressure liquid acting in a cylinder L on a piston Ll which is connected to the lever Ki, or by a spring. On the shaft vKris a second lever K2 from which extends a connection, K3 to the governor M which determines the setting of the blades of the airscrew MI in a known manner, the governor being thus adjusted through the action of the cam F3. The Vconnection Kt also actuates the ignition control mechanism M2, A shaft N coaxial with the shaft J 2 of the servomotor Jl carries the second bevel wheel E!! of the differential gear E and also a lever Nl connectred to the throttle Nfl through a link N5, and movable on it is a manually operable lever N2. This lever N2 functions as an override lever in that it carries a toothed sector N3 which meshes vwith teeth one. member Ke rotatable on the shaft K and provided with stops K which lie on each sideoi the lever K2. Thus by movement of the override lever N2 and through the stops K5 the lever K2 can be moved and thereby, and through the governor, the blades of the airscrew can be adjusted to fully fine pitch. These stops K5 as actuated by the override lever can also be used to produce other effects independently of the position of the operating lever A.

This apparatus may be designated as a servomotor actuated boost control operating through spring J3 acting on the remote end of the piston valve J of the servomotor J i. On the other hand the datum boost spring H2 tries to draw out the capsule in opposition to its tendency to move under the influence of the boost pressure. By mounting the capsule in this way it is caused to be very sensitive to changes of boost pressure since all friction is substantially eliminated between the piston valve J and the capsule owing to the transmission of movement from one to the other being by way of surfaces which are maintained in contact and not through parts pivotally connected.

YThe apparatus will now be described more in detail and with reference to Figs. 2 to 9 in which the parts are shown as they ,may be constructed and arranged inpractice. As mentioned the differential gear is of the bevel wheel type comprisingthe two wheels E3, Ei and the pinions E2 which are carried in a suitably arranged cage ,E5 rotatable about the axis of the gear.

The shafts J2 and VN on which are mounted the two main wheels ES and Eil are coaxial and extend in opposite directions as may be seen in Fig.'3. The cage E5 has on its exterior teeth El which con- ,venientlyextend only overV a portion of the pe'- riphery of the cage owing to the limited rotational movement which it is necessary to give to the page. Meshingwith the toothed sector El '.on the cage is a pinion Di on the shaft Dwhich is rotated by the action of the servomotor C.

the other.

This motor has a radial blade CI projecting from the shaft D and movable in its casing when pressure liquid is admitted to one side or the other of the blade as will occur when the pilots operating lever A is moved in one direction or The actuation of the valve B controlling the admission of this pressure liquid is effected through mechanism as otherwise known. With this mechanism, when the operating lever A is turned througha determined angle, a cylindrical valve Bi is rapidly moved thereby so as to open a port B2 leading to one side of the blade Cl of the servomotor and to admit pressure fluid thereto through passages B3. At the same time a port B4 (indicated in dotted lines) is opened on the other side of the servomotor blades Cl which communicates with a drain through passages B5. The blade Ci and the shaft D thus begin to move, but the ports B2 and B4 are formed in the shaft D to which the blade Cl is attached, and therefore move with it. This following-up arrangement ensures that the blade Cl andthe shaft D move through the same angle as that through which the valve Bxl has been turned. It will be seen that this rotation of the shaft D due to moving the operating lever A through a certain angle will cause a corresponding rotation of the cage E5 with the bevel pinions E2 about the axis of vthe differential gear and the cage and pinions will be retained in the angular position in which they are thus set until the operating lever is again moved. i

The one bevel wheel E3 of the differential gear can be rotated in one direction or the other by the action of the primary servomotor J l to which pressure is admitted according to the setting of the piston valve J. This servomotor J l is preferably of the rotary type with radial blades J l projecting'from the shaft J2 the direction in which the shaft is turned being determined by the flow of pressure liquid to and from the servomotor through the piping J 5 as permitted by the setting of the valve J, the shaft J 2 being held in the angular position into which it is moved when the flow of pressure liquid is stopped. From the siecond bevel wheel Eil through the shaft N on which it is mounted and a lever Nl on this shaft there is a connection to the engine throttle. Thus if the bevel wheel E3 after it has been angularly set by the servomotor J l is held against rotation and the operating lever A is then moved so as to cause rotation through a determined angle of the shaft D, the cage of the diierential with the pinions E2 will be turned through a corresponding angle about the axis of the gear and willthe operating lever A is not moved and the cage .Y

of the differential with the pinions'EZ is held stationary, and if pressure liquid is thenadmitted `to the servomotor J i so that it rotates the shaft J 2 and the bevel wheel E3, this will also rotate the bevel wheel Eli and the shaft N and movement will be given to the throttle. Y w

'Ihe piston valve J controlling the servomotor J can reciprocate in a ported sleeve J 5 mounted in a casing O at each end of which is a diaphragm Ol, .O2 extending across the open end of the casingthe centre part of each diaphragm lying in contact with one end of the piston valve. Each diaphragm is held by a ring O3 and they prevent oil leakage, the Vvalve itself between the diaphrams being in hydraulic balance. The piston valve J at each end is connected to one of these on bythe datum boost cam F2.

diaphragme the -xend lof lthe valve having a :threaded Lpart whichpassesithrough ahole in the :centre Vof the diaphragm -to `which it is secured by sealing washers` andnuts Oli, O5. `The nut Ofi i at the upper -end por"` the `valve conveniently has a rounded or part-spherical face. VAt the 'opposite fend rof the :valve the nut G5 has around it, and .bearing on a cupped or other suitable washer,

the one end of a coiled spring J 3 the other end -of which bears againstaiixed abutmentlOt Vcarried'lby or forming ,-part of `the-casing which encloses the whole apparatus.

A capsule I-I-which is totally evacuated is sus-- pended at its Vupper `end frorna casing P `by a threaded member :H4 which permits adjustment of `thepposition-or -thisencl of the capsule. ,EX- .tending from the lower end oi the capsule is a rod :HI' whose end bears on the rounded faceoip the=nut-4 en the uppcrfend of the piston valve J. Fixed on this rod El at or near its end is a .disc :H3 whose upperside serves as abutment `torrone end of a coiled spring H2 on the upper end oi which rests a disc -I-I which `is `pressed onto the spring b y the end of the arm Gi of the lever which through itsother arm Gis acted The spring HZ thus acts in opposition toany collapsing tendency of the capsule H which the action of the capsule .is` somewhat assisted by the spring J3 which acts on the lower end of the'valve J. rEhe capsuleand the spring H2 are enclosed in a casing P, Pi which is subjected internally to boost pressure. Apart from the connectioniof the valve J at its opposite `ends to the diaphragms Ol, O2 the Valve `floats `.between the spring Jil and the lower end of the rod Hl and this construction is accordance with the settingof the operatinglever A. To admit or anice adjustment in the-action of thefcam Fillon the spring H2, the arm G of the rlever through which the cam acts Aon the spring is-providedwith an articulated end. `This comprises,` asseenin Fig. 2,9. short lever member G3 pivoted at Gli on the end of the lever arm G and carrying at one end a roller G5 which rests on the cam F2 and at the other end an adjustable stud Gt which bears on a part of the lever arm G. By adjusting this stud it is possible to alter the angular position of the member G3 in relation to the main part of the lever arm G and this has the effect of varying the angular position of the lever G, Gl with respect to the cam F2 on the one hand and the spring H2 on the other whereby the datum boost spring H2 can be correctly set.

On the shaft F which carries the datum boost cam F2 is a second cam F3 which may be referred to as the speed cam in that it acts on the airscrew governor and on the ignition control. See Figs. 3 and 5. This action takes place through a shaft K which carries a lever Kl with a roller KG bearing on the cam F3 and a second lever K2 operatively connected in some convenient known manner, such as indicated in Figure l, to the airscrew governor M and ignition control mechanism M2. While the roller K5 on the lever Ki may be kept in contact with the cam F3 by means of a spring, it is convenient to lever. QThis.overrideflever N2 is :mounted on the shaft N, :or concentrically therewith, VSee :Figure 5,

4but :s'fnot :lined to the ,shaft and can thus be -moved separately. The lever N2 carries a toothed quadrantNal which meshes with a toothed sector on a member Kt carried by but lireelyrotatable on or concentric with the shaft K, see

.Figure 4. `On the ,member K4 are two adjustable stops K5 spaced apart circumferentially and positionedso that theyflie on each side of the controlllever K2. By this means if the override lever vNil lislturned it is `possible to move the speed control lever KZ intoitsliinit position and thereby cause the `airscrew blades to be set to` fully line pitch. When the operatingr lever A is Vin the `closed position, `that is to say when the throttle Vvalve actuated `by-,this lever is shut, a depression `in `the, profile of the speed cam allows the speed `control lever .K2 to be moved in the opposite `direction to the limit of its travel which will result in setting the air screw blades in the positive coarse or in the featheredposition This iposition can only bereached `when the override lever NZ has been set tothe position for posi- ,tivecoarse settingfofthexair screw. ,Ii the over Aride leverlll Vis leitin its normal position the speed .control lever K2 will vmove automatically rointheposition to, produce coarse pitch or'minimum yrevclutions totheposition to produce iine .pitch :or maximum revolutions `when the speed cainll'zis turnedby the pilotsoperating lever.

.Referring againzto ,the valveJ controlling the primary servomotor J i, when this valve is in its central lor `sensitive,,position l pressure `liquid is cut `oit-from the servomotor, but if the valve is caused ,to move towards the capsule oilis admitted to the servomotorlin a manner which will cause it 1to1-close -the'throttle by acting through the dif- .ierential irgear.

Conversely when the `valve J moves away from the capsule the .dow of oil to .thelservornotorJ l will `cause it similarly `toopen the throttle. Anyimovementzof the; lever G, Gi :actuatedby ltheadatumboost cani F2 byfits action on the spring H2 will upset the balance of the system and cause a movement of the piston valve J thereby changing the opening of the throttle. On account of the wide range of boost pressures required it is advantageous, as in the present arrangement, to have outside the capsule H a spring H2 by which the capsule datum is varied. With an internal capsule spring load variations on the spring are only obtained by allowing the capsule as a whole to change in length, but with the present method the capsule movement can be limited to plus or minus three thirty-seconds of an inch. This permits the use of a much shorter capsule and also completely eliminates any fatigue stresses in the capsule. With regard to the subsidiary servomotor C the controller of this is conveniently constructed so that its anguiar movement relative to the movement of the operating lever is stepped up in a ratio of 4 to l. rhis gives a quick valve opening for the operation of the servomotor. The gearing actuating the camshaft may be such that this shaft will turn for example at twice the speed at which the servomotor shaft is turned and this enables reasonable cam proles to be employed.

v Theboost control embodied in the present invention may be referred to as being of the reverse action type in that the butterfly or throttle valves are opened a small amount mechanically and the necessary extra movement to obtain any required selected boost is supplied by the automatic action of the servomotor J l in rotating one of the Wheels of the differential. This system of operation allows the pilot to climb at any selected boost to the maximum altitude possible corresponding to that boost without resetting the operating lever, because with the loW- est boost setting likely to be used for climbing there is sufficient automatic movement available in the primary servomotor to fully open the throttle valve.

The automatic part ofthe present control apparatus is rendered inoperative at low engine speeds. It has been found desirable to do this on `account of the unstable behaviour of the boost pressures obtaining when the supercharger is running at low speeds. By so shaping the datum boost cam F2 that the boost called for is less than the actual boost obtained from the engine, the point at which the servomotor J l begins to operate can be controlled. In such a single lever control system as the present this should be coincidentewith the point at which the air screw governor begins to operate.

What I claim as my invention and desire to secure by Letters Patent is:

1. Apparatus for the control of an internal combustion engine for driving an air screw and comprising a super-charger, a pitch changing device provided with a governor, an ignition system and a control therefor, and a throttle valve, in combination with a differential gear, a connection between the rst main wheel of this gear and the engine throttle through which the throttle can be adjusted, a primary servomotor operative to rotate the second and opposite main Wheel in the said differential gear, a secondary servomotor with means Vfor controlling it by an operating lever, means by which the cage with the pinions of the said differential gear can be rotated about the axis of the gear by the said secondary servomotor, a valve controlling the ilow of pressure liquid to the said primary servomotor, a capsule subject on the one hand to the engine boost pressure and on the other hand toV the action of a spring, a connection between the capsule and the said control valve of the said primary servomotor, a cam shaft with means for rotating it by the said secondary servomotor when this motor is operative to move the pinion cage of the said differential gear, a datum boost cam on the said cam shaft operative to vary the force exerted by the said spring on the said capsule and thus effect the setting by the capsule of the said valve of the said primary servomotor, a second cam on the said cam shaft, transmission means from said second cam operative on said airscrew governor and on the engine ignition control, an override lever operative on the airscrew governor and the engine ignition, a rotatable member included in said transmission means from said second cam on the cam shaft, stops spaced circumferentially apart on this member, a lever movable between these stops With a connection from this lever to means for setting the airscrew governor and the engine ignition, and a connection between said override lever and said stop-carrying member.

2. Apparatus for the control of an internal combustion engine comprising the parts asset out in claim 1 and in Which the control valve of the said primary servomotor is a piston valve mounted so that it iioats between two diaphragins'serving as oil seals at the opposite end of the valve, the valve being balanced on the one hand by its connection to the said capsule and the conse-V quent tendency for the valve to be moved in one direction by the action of the boost pressure on the capsule together with the action of a spring operative on the end of the valve, and on the other hand by the said spring which acts on the capsule.

ADRlAN LESLIE CATFORD.

REFERENCES CITED The following references are of record in the le of this patent: l

UNITED STATES PATENTS Number Name Date 2,115,485 Dodson Apr. 26, 1938 2,217,364 Halford Oct. 8, 1940 Y2,383,719 Halford et al. Aug. 28, 1945 2,453,651 Mock Nov. 9, 1948 2,457,595 Orr Dec. 28, 1948 

